Board printing apparatus and board printing method

ABSTRACT

A board printing apparatus includes a board working table, a first printing table, a second printing table, and a control portion controlling printing operations. The control portion is configured to perform second printing on a board held by the board working table by a large component mask of the second printing table after a first printing performed on the board held by the board working table by a small component mask of the first printing table.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of priority to Japanese PatentApplication No. 2012-277468 filed on Dec. 19, 2012, the entire contentof which is incorporated herein by reference.

TECHNICAL FIELD

The technical field relates to a board printing apparatus and a boardprinting method, and more particularly, it relates to a board printingapparatus performing mask-printing on a board and a board printingmethod.

BACKGROUND

A board printing apparatus performing mask-printing on a board is knownin general. Such a board printing apparatus is disclosed in JapanesePatent Laying-Open No. 2006-066811, for example.

Due to miniaturization of electronic components mounted on a printedboard, 0603 size (0.6 mm×0.3 mm) or 0402 size (0.4 mm×0.2 mm) smallcomponents (very small components) and large components such as a shieldcomponent are mixed and mounted on the board. When a viscous materialsuch as solder is printed on the board to mount these components, anappropriate amount of transfer of the viscous material to be printed isgenerally determined according to the size of a component according tothe size of the component.

Japanese Patent Laying-Open No. 2006-066811 discloses a technology toprint solder using a single mask (so-called half etching mask) having alarge thickness in a printing area corresponding to a large componentand a small thickness in a printing area corresponding to a smallcomponent (very small component). The amount of transfer of a viscousmaterial on a board corresponds to the thickness of the mask, so thatthe viscous material can be printed with the amount of materialaccording to the size of a component by using the half etching mask.When the mask disclosed in Japanese Patent Laying-Open No. 2006-066811is used, however, a step (a boundary between the thickness for the largecomponent and the thickness for the small component) is formed in theprinting area, and stable printing pressure for filling an opening withthe viscous material cannot be ensured in the vicinity of this step.Thus, a circuit pattern (an opening pattern of the mask) must be formedto avoid the vicinity of the step. Therefore, according to the printingtechnology disclosed in Japanese Patent Laying-Open No. 2006-066811, theintegration degree of a circuit cannot be improved.

Two types of masks, a first mask for the small component having thesmall thickness and a second mask for the large component having thelarge thickness, are conceivably prepared to sequentially performprinting. A relief portion is provided on the board contact surface ofthe second mask to relieve a pattern of a transfer material formed bythe first mask, whereby a printing pattern for the large component canbe formed by the second mask after a printing pattern for the smallcomponent (very small component) is formed by the first mask.

When the two types of masks are used, however, two board printingapparatuses must be provided to create a production line forsequentially performing printing, and hence the structure of theproduction line is disadvantageously complicated.

SUMMARY

The present disclosure has been proposed in order to solve theaforementioned problem, and an object of the present disclosure is toprovide a board printing apparatus and a board printing method eachcapable of producing a board without complicating the structure of aproduction line even when two types of masks, a small component mask anda large component mask, are used to perform printing.

In order to attain the aforementioned object, a board printing apparatusaccording to a first aspect of the present disclosure includes a boardworking table holding a board to be printed on. A first printing tableand a second printing table are aligned in a prescribed direction in ahorizontal direction above the board working table, and a controlportion controls the printing operations of the first printing table andthe second printing table, and while the first printing table holds asmall component mask having a first thickness configured to perform afirst printing to print a viscous material on the board, the secondprinting table holds a large component mask having a second thicknessthicker than the first thickness, formed with a relief portion having adepth larger than the first thickness on a board contact surface torelieve the viscous material printed by the small component mask,configured to perform a second printing to print the viscous material onthe board after the first printing by the first printing table. Theboard working table and at least one of the first printing table and thesecond printing table are configured to be movable in the prescribeddirection in the horizontal direction. The board working table and atleast one of the first printing table and the second printing table areconfigured to be movable in a vertical direction. The control portion isconfigured to perform the second printing on the board held by the boardworking table by the large component mask of the second printing tableafter the first printing performed on the board held by the boardworking table by the small component mask of the first printing table.

In the board printing apparatus according to the first aspect of thepresent disclosure, as hereinabove described, the first printing tableholds the small component mask configured to perform the first printingto print the viscous material on the board. The second printing tableholds the large component mask formed with the relief portion having thedepth larger than the first thickness on the board contact surface torelieve the viscous material printed by the small component mask,configured to perform the second printing to print the viscous materialon the board after the first printing performed by the first printingtable. The control portion is configured to perform the second printingon the board held by the board working table by the large component maskof the second printing table after the first printing performed on theboard held by the board working table by the small component mask of thefirst printing table. Thus, the first printing using the small componentmask (very small component mask) and the second printing using the largecomponent mask can be performed by the single board printing apparatus.Thus, it is not necessary to provide two board printing apparatuses in aproduction line, and hence the board can be produced withoutcomplicating the structure of the production line even in the case whereprinting is performed using two types of masks, the small component maskand the large component mask.

In the aforementioned board printing apparatus according to the firstaspect, the control portion is preferably configured to perform theprinting preparation operation of one of the first printing table andthe second printing table during the board printing operation of theother of the first printing table and the second printing table.According to this structure, the preparation operation for subsequentprinting can be performed in advance in one of the first printing tableand the second printing table, utilizing a standby period during theboard printing operation of the other of the first printing table andthe second printing table. Consequently, the time required for boardprinting (the time required for the board printing operation and theprinting preparation operation) can be reduced even in the case wherethe first printing and the second printing are performed by the singleboard printing apparatus.

In this case, the first printing table and the second printing table arepreferably configured to be movable in the prescribed direction in thehorizontal direction, and the control portion is preferably configuredto move the second printing table closer to a printing position bymoving the second printing table in the prescribed direction in thehorizontal direction such that a distance between the first printingtable and the second printing table is reduced in the prescribeddirection in the horizontal direction during the board printingoperation of the first printing table. According to this structure, partof the operation of the movement of the second printing table to theprinting position can be performed during the board printing operationof the first printing table, and hence the time required for boardprinting can be reduced when the second printing is performed by thesecond printing table.

In the aforementioned structure in which the second printing table ismoved closer to the printing position during the board printingoperation of the first printing table, the control portion is preferablyconfigured to move the second printing table closer to the printingposition until an interval between the second printing table and thefirst printing table becomes an accessible minimum interval withoutinterference during the board printing operation. According to thisstructure, the second printing table can be moved as close as possibleto the printing position during the board printing operation of thefirst printing table, and hence the time required for board printing canbe effectively reduced when the second printing is performed by thesecond printing table.

In this case, the control portion is preferably configured to locate thesecond printing table at the printing position by moving the firstprinting table and the second printing table while keeping a distanceequal to or more than the minimum interval when the second printing isperformed by the second printing table after the second printing tableis moved closer to the printing position. According to this structure,when it is necessary to evacuate the first printing table in order tolocate the second printing table at the printing position, for example,the time required for the movement of the second printing table to theprinting position can be reduced, as compared with the case where thefirst printing table and the second printing table are moved in order(individually).

In the aforementioned structure in which the printing preparationoperation of one of the first printing table and the second printingtable is performed during the board printing operation of the other ofthe first printing table and the second printing table, the firstprinting table and the second printing table are preferably configuredto be movable in the vertical direction, and the control portion ispreferably configured to lower the second printing table from the largecomponent mask plate releasing height position of the large componentmask separated from the board after the second printing of the viscousmaterial to a standby height position lower than the large componentmask plate releasing height position, where the viscous material on theboard is in non-contact with the large component mask during a boardprinting operation using the small component mask of the first printingtable. According to this structure, during the board printing operation(first printing) of the first printing table, part of the loweringoperation for registering the large component mask to the board can beperformed in the second printing table. Consequently, the time requiredfor board printing can be reduced when the second printing is performedby the second printing table.

In this case, the standby height position preferably includes a heightposition determined on the basis of at least the first thickness of thesmall component mask and the amount of deflection of the large componentmask. According to this structure, the viscous material having a heightcorresponding to the first thickness is formed on the board after thefirst printing when the second printing is performed, and hence thelarge component mask can be arranged at the standby height positionwhere the large component mask is moved as close as possible to theboard after the first printing in consideration of the first thicknessand the amount of deflection of the large component mask. Thus, the timerequired for board printing can be effectively reduced when the secondprinting is performed by the second printing table.

In the aforementioned structure in which the printing preparationoperation of one of the first printing table and the second printingtable is performed during the board printing operation of the other ofthe first printing table and the second printing table, the boardworking table preferably includes a first board working table and asecond board working table each configured to be movable in theprescribed direction in the horizontal direction. Each of the firstboard working table and the second board working table preferably has amask recognition camera capable of recognizing the small component maskand the large component mask. The control portion is preferablyconfigured to perform mask recognition of the large component mask ofthe second printing table using the second board working table during aboard printing operation performed by the first board working table andthe first printing table using the small component mask. According tothis structure, the mask recognition for aligning the large componentmask with the board can be performed in advance in the second printingtable during the board printing operation (first printing) of the firstprinting table using the small component mask. Consequently, the secondprinting can be immediately performed by the large component mask thathas been already recognized after the first printing, and hence the timerequired for board printing can be reduced when the second printing isperformed.

In this case, the control portion is preferably configured to performthe mask recognition of the large component mask using the second boardworking table at least when a board printing operation is firstperformed by the first board working table and the first printing table.According to this structure, it is necessary to align the mask with theboard by the mask recognition operation when the board printingoperation is first performed, and hence at least the first maskrecognition operation is performed in advance, whereby the secondprinting can be immediately started. If mask recognition is performed atleast when the printing is first performed, the mask recognition can beskipped by utilizing the prior mask recognition result.

In the aforementioned structure in which the printing preparationoperation of one of the first printing table and the second printingtable is performed during the board printing operation of the other ofthe first printing table and the second printing table, the boardworking table preferably includes a first board working table and asecond board working table each configured to be movable in theprescribed direction in the horizontal direction. Each of the firstboard working table and the second board working table preferably has acleaning unit configured to clean the small component mask and the largecomponent mask. The control portion is preferably configured to performa mask cleaning operation for the small component mask of the firstprinting table using the first board working table while the secondboard working table and the second printing table perform a boardprinting operation on the board after the first printing using the largecomponent mask. According to this structure, the mask cleaning operationfor the small component mask can be performed in the first printingtable during the board printing operation (second printing) of thesecond printing table after the board printing (first printing) of thefirst printing table. Consequently, the time required for the printingpreparation operation can be reduced when the first printing isperformed on a subsequent board by the first printing table.

In this case, the first printing table and the second printing table arepreferably configured to be movable in the prescribed direction in thehorizontal direction. The control portion is preferably configured tomove the first printing table in a direction away from the secondprinting table and perform the mask cleaning operation for the smallcomponent mask at a position separated from the second printing tablewhile the second board working table and the second printing tableperform the board printing operation. According to this structure, thefirst printing table can be separated from the second printing tableduring the mask cleaning operation, and hence a work space for the maskcleaning operation can be ensured during the second printing performedby the second printing table.

In the aforementioned structure in which the printing preparationoperation of one of the first printing table and the second printingtable is performed during the board printing operation of the other ofthe first printing table and the second printing table, the boardworking table preferably includes a first board working table and asecond board working table each configured to be movable in theprescribed direction. The control portion is preferably configured toperform at least one of the operations of carrying the board into one ofthe first board working table and the second board working table andcarrying the board out of the other of the first board working table andthe second board working table during a board printing operationperformed by one of the first printing table and the second printingtable and the other of the first board working table and the secondboard working table. According to this structure, at least one of theoperations of carrying the board into one of the first board workingtable and the second board working table and carrying the board out ofthe other of the first board working table and the second board workingtable can be performed during the board printing operation performed bythe other of the first board working table and the second board workingtable, and hence the time required for the printing preparationoperation (the operation of carrying the board into one of the firstboard working table and the second board working table and the operationof carrying the board out of the other of the first board working tableand the second board working table) can be reduced when printing isperformed on the subsequent board even in the case where the firstprinting and the second printing are performed by the single boardprinting apparatus.

In the aforementioned board printing apparatus according to the firstaspect, the board working table preferably includes a first boardworking table and a second board working table each configured to bemovable in the prescribed direction. The control portion is preferablyconfigured to perform a board printing operation of the first printingon a second board before the first printing by the first printing tableand one of the first board working table and the second board workingtable during a board printing operation of the second printing performedon a first board after the first printing by the second printing tableand the other of the first board working table and the second boardworking table. According to this structure, during the second printingperformed on the first board, the first printing can be performed inadvance on a board (second board) to be printed on next. Consequently,the time required for the board printing operation can be reduced whenprinting is performed on the subsequent board even in the case where thefirst printing and the second printing are performed by the single boardprinting apparatus.

A board printing method according to a second aspect of the presentdisclosure is a board printing method of a board printing apparatusincluding a first printing table and a second printing table eachconfigured to print a viscous material on a board and includes the stepsof performing first printing on the board held by a board working tableby a small component mask of the first printing table and performingsecond printing on the board held by the board working table after thefirst printing by a large component mask of the second printing table.

As hereinabove described, this board printing method according to thesecond aspect of the present disclosure includes the steps of performingthe first printing on the board held by the board working table by thesmall component mask of the first printing table and performing thesecond printing on the board held by the board working table after thefirst printing by the large component mask of the second printing table,whereby the first printing using the small component mask (very smallcomponent mask) and the second printing using the large component maskcan be performed by the single board printing apparatus. Thus, it is notnecessary to provide two board printing apparatuses in a productionline, and hence the board can be produced without complicating thestructure of the production line even in the case where printing isperformed using two types of masks, the small component mask and thelarge component mask.

The aforementioned board printing method according to the second aspectpreferably further includes a step of performing a printing preparationoperation performed for one of the step of performing the first printingby the first printing table and the step of performing the secondprinting by the second printing table during a board printing operationof the other of the step of performing the first printing by the firstprinting table and the step of performing the second printing by thesecond printing table. According to this structure, the preparationoperation for subsequent printing can be performed in advance in one ofthe first printing table and the second printing table, utilizing astandby period during the board printing operation of the other of thefirst printing table and the second printing table. Consequently, thetime required for board printing (the time required for the boardprinting operation and the printing preparation operation) can bereduced even in the case where the first printing and the secondprinting are performed by the single board printing apparatus.

The foregoing and other objects, features, aspects and advantages of thepresent disclosure will become more apparent from the following detaileddescription of the present disclosure when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically showing a printing apparatusaccording to a first embodiment of the present disclosure.

FIG. 2 is a side elevational view schematically showing the printingapparatus according to the first embodiment of the present disclosure asviewed in a direction Y.

FIG. 3 is a sectional view schematically showing a board working tableconstituting the printing apparatus according to the first embodiment ofthe present disclosure as viewed in a direction X.

FIG. 4 is a schematic view showing a small component mask of theprinting apparatus according to the first embodiment of the presentdisclosure.

FIG. 5 is a schematic view showing a large component mask of theprinting apparatus according to the first embodiment of the presentdisclosure.

FIG. 6 is a block diagram showing the control structure of a printingapparatus according to first to sixth embodiments of the presentdisclosure.

FIG. 7 is a control flowchart showing the operational outline of theprinting apparatus according to the first embodiment of the presentdisclosure during a board printing operation.

FIG. 8 is a schematic view showing the positional relationship of theprinting apparatus according to the first embodiment of the presentdisclosure during the board printing operation (when a board is carriedinto the printing apparatus).

FIG. 9 is a schematic view showing the positional relationship of theprinting apparatus according to the first embodiment of the presentdisclosure during the board printing operation (first printing).

FIG. 10 is a schematic view showing the positional relationship of theprinting apparatus according to the first embodiment of the presentdisclosure during the board printing operation (second printing).

FIG. 11 is a schematic view showing the positional relationship of theprinting apparatus according to the first embodiment of the presentdisclosure during the board printing operation (when the board iscarried out of the printing apparatus).

FIG. 12 is a schematic view for illustrating an advance approachoperation of the printing apparatus according to the second embodimentof the present disclosure.

FIG. 13 is a schematic view showing the positional relationship of theprinting apparatus according to the second embodiment of the presentdisclosure during a board printing operation (first printing).

FIG. 14 is a schematic view showing the positional relationship of theprinting apparatus according to the second embodiment of the presentdisclosure during the board printing operation (second printing).

FIG. 15 is a schematic view for illustrating an advance loweringoperation of the printing apparatus according to the third embodiment ofthe present disclosure.

FIG. 16 is a schematic view showing the positional relationship of theprinting apparatus according to the fourth embodiment of the presentdisclosure during a board printing operation (first printing) forillustrating advance mask recognition.

FIG. 17 is a control flowchart showing the operational outline of theprinting apparatus according to the fifth embodiment of the presentdisclosure during a board printing operation for illustrating an advancecleaning operation.

FIG. 18 is a schematic view showing the positional relationship of theprinting apparatus according to the fifth embodiment of the presentdisclosure during the board printing operation (second printing) forillustrating the advance cleaning operation.

FIG. 19 is a control flowchart (first half) showing the operationaloutline of the printing apparatus according to the sixth embodiment ofthe present disclosure during a board printing operation.

FIG. 20 is a control flowchart (second half) showing the operationaloutline of the printing apparatus according to the sixth embodiment ofthe present disclosure during the board printing operation.

FIG. 21 is a schematic view showing the positional relationship of theprinting apparatus according to the sixth embodiment of the presentdisclosure during the board printing operation (an operation of carryinga board into the printing apparatus, an operation of carrying the boardout of the printing apparatus, and first printing).

FIG. 22 is a schematic view showing the positional relationship of theprinting apparatus according to the sixth embodiment of the presentdisclosure during the board printing operation (first printing andsecond printing).

FIG. 23 is a schematic view showing the positional relationship of theprinting apparatus according to the sixth embodiment of the presentdisclosure during the board printing operation (an operation of carryinga board into the printing apparatus, an operation of carrying the boardout of the printing apparatus, and second printing).

DETAILED DESCRIPTION

Embodiments of the present disclosure are hereinafter described withreference to the drawings.

First Embodiment

The structure of a printing apparatus 100 according to a firstembodiment of the present disclosure is now described with reference toFIGS. 1 to 6. In the first embodiment, the “board printing apparatus”according to the present disclosure is applied to the printing apparatus100.

The printing apparatus 100 according to the first embodiment of thepresent disclosure is a board printing apparatus mask-printing solderpaste on the upper surface of a printed board (hereinafter referred toas the “board”) 5 conveyed into an apparatus body, as shown in FIGS. 1to 3.

As shown in FIG. 1, the printing apparatus 100 is configured to becapable of carrying the board 5 thereinto from a loader DL1 at acarry-in position Ent and from a loader LD2 at a carry-in position Enton the upstream side in a conveyance direction (the right side in adirection X) and to carry the board 5 on which printing has beenperformed thereout to an apparatus M on the downstream side in theconveyance direction (the left side in the direction X) through acarry-out position Ex1 or Ex2 on the downstream side. The carry-outpositions Ex1 and Ex2 are aligned with the carry-in positions En1 andEnt in the direction X, respectively. The conveyance direction of theboard 5 is the direction X, and a direction orthogonal to the directionX in a horizontal plane is a direction Y. A vertical directionorthogonal to the directions X and Y is a direction Z. The direction Yis an example of the “prescribed direction in a horizontal direction” inthe present disclosure. Due to this structure, the printing apparatus100 partially constitutes a board production line of a printed circuitboard having two conveyance lines.

The printing apparatus 100 includes a base 1, two board working tables 2a and 2 b holding and conveying the board 5, two printing tables 3 a and3 b, and two squeegee units 4 a and 4 b. The board working table 2 a,the printing table 3 a, and the squeegee unit 4 a are arranged on the Y2side of the printing apparatus 100, and the board working table 2 b, theprinting table 3 b, and the squeegee unit 4 b are arranged on the Y1side of the printing apparatus 100. A controller 80 (see FIG. 6)described later configured to control the operation of each partdescribed below is incorporated in the printing apparatus 100. The boardworking tables 2 a and 2 b are examples of the “first board workingtable” and the “second board working table” in the present disclosure,respectively. The printing tables 3 a and 3 b are examples of the “firstprinting table” and the “second printing table” in the presentdisclosure, respectively.

The two board working tables 2 a and 2 b are aligned in the direction Yand have functions of receiving the board 5 at the correspondingcarry-in positions En1 and En2, supporting and fixing the board 5 whilebeing opposed to the printing tables 3 a and 3 b during a printingoperation, and carrying the board 5 on which printing has been performedthereout through the corresponding carry-out positions Ex1 and Ex2. Thecarry-in position En1 and the carry-out position Ex1 on the Y2 sidecorrespond to the board working table 2 a, and the carry-in position En2and the carry-out position Ex2 on the Y1 side correspond to the boardworking table 2 b.

As shown in FIGS. 1 to 3, the board working tables 2 a and 2 b eachinclude a movable stand 21 configured to be movable in the direction Y,a conveying conveyor 22 including a pair of conveyor rails extending inthe conveyance direction (direction X) arranged on the movable stand 21,a clamp unit 23 configured to be movable in the direction X whileholding (fixing) the board 5 to allow a printing operation in a statewhere the board 5 on the conveying conveyor 22 is separated upward fromthe conveying conveyor 22, a mask recognition camera 24 provided on theclamp unit 23, and a cleaning unit (see FIG. 3) arranged on the movablestand 21. The board working table 2 a is substantially similar instructure to the board working table 2 b, and hence the individualdescription is omitted.

As shown in FIG. 1, the movable stand 21 is supported to be movable inthe direction Y on a guide rails 11 extending in the direction Y on thebase 1. The movable stands 21 of the board working tables 2 a and 2 bare configured to be moved individually in the direction Y on the guiderail 11 by two table drive mechanisms. Specifically, the movable stands21 of the board working tables 2 a and 2 b are driven in the direction Yby screw shafts 12 a and 12 b extending in the direction Y andservomotors 13 a and 13 b drivingly rotating the screw shafts 12 a and12 b, respectively, as shown in FIG. 3. Thus, the board working tables 2a and 2 b are configured to be individually movable along a Y-axis (inthe direction Y) to at least the positions of the printing tables 3 aand 3 b on an opposite side in the direction Y and have common movementregions (the movement ranges overlap with each other).

As shown in FIGS. 1 and 2, the conveying conveyor 22 is provided toextend over the substantially entire length of the printing apparatus100 in the direction X and can carry the board thereinto and thereout byaligning the position of the conveying conveyor 22 with the Y-axiscoordinates of the carry-in position En1 (En2) and the carry-outposition Ex1 (Ex2). Each conveying conveyor 22 can move one of the pairof conveyor rails in the direction Y on the movable stand 21 and changethe conveyor width (an interval between the conveyor rails) according tothe size of the conveyed board 5.

As shown in FIG. 3, the clamp unit 23 is a movable unit provided to holdthe conveying conveyor 22 including the pair of conveyor rails from bothouter sides in the direction Y. The clamp unit 23 is configured to bemovable in the direction X on guide rails 51 a by an X-axis movementmechanism (see FIG. 2) extending in the direction X provided on themovable stand 21. Thus, the clamp unit 23 is movable in the direction Xalong the conveying conveyor 22. The width of the clamp unit 23 in thedirection Y can be changed according to the conveyor width of theconveying conveyor 22.

The clamp unit 23 includes a clamp mechanism 52 configured to grasp andfix the board 5 and a support mechanism 53 configured to lift andsupport the board 5 on the conveying conveyor 22. The clamp mechanism 52is configured to be capable of holding the board 5 on the conveyingconveyor 22 from both sides in the direction Y and grasping the board 5by driving an unshown air cylinder and displacing a clamp portion 52 bin a direction approaching a clamp portion 52 a. If the air cylinder isactivated in an opposite direction, the clamp is released.

The support mechanism 53 includes a backup pin 53 a and a lift mechanism53 b vertically moving the backup pin 53 a and is configured to lift andsupport the board 5 on the conveying conveyor 22 by the lift mechanism53 b and the backup pin 53 a by bringing the backup pin 53 a intocontact with the lower surface of the board 5 from below. The board 5lifted by the support mechanism 53 is grasped by the clamp mechanism 52,whereby the board 5 is fixedly held in a state separated above from theconveying conveyor 22, and a printing operation can be performed on theboard 5 on the board working table 2 a (2 b).

The mask recognition camera 24 includes a CCD area sensor etc. and ismounted on the outside of the clamp unit 23 in the direction Y such thatthe imaging direction faces upward. Therefore, the mask recognitioncamera 24 is movable in the direction Y due to the movement of the boardworking table 2 a (2 b) and is movable in the direction X due to themovement of the clamp unit 23. The mask recognition camera 24 isprovided to image mask recognition marks Q (see FIG. 8) attached to thelower sides of screen masks (a small component mask 6 and a largecomponent mask 7 described later) held by the printing tables 3 a and 3b from below and recognize the positions and postures of the masks (thesmall component mask 6 and the large component mask 7).

The detailed illustration of the cleaning unit 25 is omitted, but thecleaning unit 25 includes a cleaning head having a pad brought intocontact with the board contact surfaces (lower surfaces) of the screenmasks (the small component mask 6 and the large component mask 7) and asuction nozzle performing negative-pressure suction through the pad. Theboard working table 2 a (2 b) and the masks are relatively moved (slid)in the direction Y in a state where the cleaning head is brought intocontact with the board contact surfaces of the masks, whereby solderpaste attached to the board contact surfaces or openings of the maskscan be removed. The cleaning head can move up and down vertically withrespect to the board working table 2 a (2 b), and is configured toevacuate to a lower position where the cleaning head is not in contactwith the masks except for during mask cleaning.

As shown in FIGS. 2 and 3, a pair of frame structures 14 provided toextend in the direction Y over the two board working tables 2 a and 2 bare arranged on the base 1 at a prescribed interval in the direction X(in the board conveyance direction). Each of the frame structures 14 hasa portal structure and includes a pair of legs 14 a extending upwardfrom the vicinities of both ends of the base 1 in the direction Y and abeam 14 b connecting the upper ends of the legs 14 a to each other inthe horizontal direction.

Two board recognition cameras 15 (see FIG. 3) are fixedly set on thelower side of a frame structure 14 (beam 14 b) on the upstream side inthe conveyance direction (the right side in FIG. 1) straddling over theboard working tables 2 a and 2 b. The two board recognition cameras 15are provided corresponding to the board working tables 2 a and 2 b andare arranged at a prescribed interval in the direction Y. These boardrecognition cameras 15 each include a CCD area sensor etc. and are setsuch that the imaging direction faces downward. The board recognitioncameras 15 each are configured to image unshown board recognition marksattached to the upper surface of the board 5 and recognize the positionand posture of the board 5 grasped by the clamp unit 23.

As shown in FIGS. 1 and 2, both sides of each of the printing tables 3 aand 3 b in the direction X are supported by a pair of guide rails 33 aprovided on the pair of frame structures 14, and the printing tables 3 aand 3 b are arranged above the board working tables 2 a and 2 b. Theprinting tables 3 a and 3 b each are configured to be movable in thedirection Y along the guide rails 33 a extending in the direction Y andbe movable vertically (in the direction Z). Specifically, the printingtables 3 a and 3 b each have a substantially rectangular mask fixingmember 31 detachably mounted with a screen mask, a mask lift mechanism32 moving (moving along a Z-axis) the mask fixing member 31 up and down,and a pair of mask drive mechanisms 33 configured to rotate the maskfixing member 31 about the Z-axis and move the mask fixing member 31 inthe direction Y.

According to the first embodiment, the mask fixing member 31 of theprinting table 3 a is mounted with the small component mask (very smallcomponent mask) 6. The small component mask 6 is formed with minuteopenings 6 a in a pattern corresponding to lands of a 0603 size or 0402size small component, for example, as shown in FIG. 4. The thickness ofthe small component mask 6 is a first thickness Th1 (about 50 μm toabout 75 μm, for example) appropriate for a small component. Solderprinting is performed with the small component mask 6, whereby solderSd1 having a solder height H1 appropriate for a small component isformed on a surface (printing surface) of the board 5. The solder heightH1 is equal to the first thickness Th1 or slightly smaller than thefirst thickness Th1 due to gravity acting on the solder Sd1. The solderSd1 is an example of the “viscous material” in the present disclosure.

On the other hand, the mask fixing member 31 of the printing table 3 bis mounted with the large component mask 7, as shown in FIG. 1. Thelarge component mask 7 is formed with openings 7 a in a patterncorresponding to lands of a large component such as a shield component,as shown in FIG. 5. The thickness of the large component mask 7 is asecond thickness Th2 (about 150 μm, for example) appropriate for a largecomponent, larger than the thickness of the small component mask 6. Arecessed relief portion 7 b is formed on the board contact surface(lower surface) of the large component mask 7 to cover a prescribedregion corresponding to the opening pattern of the small component mask6. The depth D of the recessed relief portion 7 b is larger than thethickness (first thickness) Th1 of the small component mask 6 (i.e.Th2>Th1). Thus, the depth D is larger than the solder height H1 of thesolder Sd1 formed by the small component mask 6. Therefore, when thelarge component mask 7 is registered to the board 5 after first printingusing the small component mask 6, the solder Sd1 formed by the smallcomponent mask 6 fits into the recessed relief portion 7 b, and thelarge component mask 7 and the solder Sd1 are kept out of contact. Inthis state, solder printing is performed with the large component mask7, whereby in addition to the solder Sd1, solder Sd2 having a solderheight H2 (the solder height H2 is equal to the second thickness Th2 orslightly smaller than the second thickness Th2 due to gravity acting onthe solder Sd2, and H2>H1) appropriate for a large component is formedon the board 5. The solder Sd2 is an example of the “viscous material”in the present disclosure.

As shown in FIG. 2, the mask lift mechanism 32 is configured to supportthe mask fixing member 31 and move the mask fixing member 31 up and downby an unshown guide, an unshown screw shaft, and an unshown Z-axis motordriving the screw shaft. Both ends of the mask lift mechanism 32 in thedirection X are supported on the pair of guide rails 33 a.

The pair of mask drive mechanisms 33 include the pair of guide rails 33a, screw shafts 33 b (see FIG. 1), and Y-axis motors 33 c driving thescrew shafts 33 b and are set on the pair of frame structures 14. Thepair of mask drive mechanisms 33 are configured to be capable of drivingthe mask lift mechanism 32 in the direction Y from both sides in thedirection X. If the pair of mask drive mechanisms 33 are driven at thesame speed, the mask lift mechanism 32 as well as the mask fixing member31 can be moved in the direction Y in a parallel fashion, and if thepair of mask drive mechanisms 33 are driven at different speeds, themask lift mechanism 32 as well as the mask fixing member 31 can berotated in the horizontal plane (X-Y plane).

Thus, the printing table 3 a (3 b) can perform printing on the board 5at an arbitrary position in the direction Y within a movement range andcan minutely align the held small component mask 6 (large component mask7) (the position in the direction Y and the inclination in thehorizontal plane) in the X-Y plane. The position in the direction X isaligned by movement adjustment of the clamp unit 23. The printing table3 a (3 b) is configured to move down along arrow Z2 by the mask liftmechanism 32 and perform a plate registering operation of bringing thesmall component mask 6 (large component mask 7) into contact with theupper surface of the board 5 during printing and to move up along arrowZ1 and perform a plate releasing operation of releasing the smallcomponent mask 6 (large component mask 7) from the upper surface of theboard 5 after printing.

In this manner, according to the first embodiment, the printingapparatus 100 divides opening patterns of the single board 5 for solderprinting into the small component mask 6 (the pattern of the openings 6a for a small component) and the large component mask 7 (the pattern ofthe openings 7 a for a large component) having the different thicknessesand prints solder individually. Thus, the solder Sd1 and solder Sd2 eachhaving an aspect ratio (the solder height/the base area of the solder,i.e. the mask thickness/the opening area) according to the componentsize can be formed on the surface (printing surface) of the board 5.

As shown in FIGS. 1 and 2, the squeegee units 4 a and 4 b each aresupported at a central portion of a movable beam 42 extending in thedirection X and are arranged above the corresponding printing table 3 a(3 b). The squeegee unit 4 a and 4 b each include a squeegee 41 (seeFIG. 2) sliding back and forth in the direction Y while pressing solderpaste against the upper surface (Z1 side) of the small component mask 6(large component mask 7), an unshown lift mechanism moving the squeegee41 up and down during printing, and an unshown squeegee angle variablemechanism configured to vary the inclination direction and inclinationangle of the squeegee 41 with respect to the small component mask 6(large component mask 7). The movable beam 42 is movably supported on apair of guide rails 43 provided to extend in the direction Y on theupper surfaces of the pair of frame structures 14. The movable beam 42is configured to be movable in the direction Y by a screw shaft 44extending in the direction Y, provided in the frame structures 14 and asqueegee shaft motor 45. The squeegee unit 4 a (4 b) as well as thesqueegee 41 is moved in the direction Y following the movement of themovable beam 42 to perform a printing operation. The squeegee unit 4 aperforms printing on the board 5 using the corresponding printing table3 a (small component mask 6), and the squeegee unit 4 b performsprinting on the board 5 using the corresponding printing table 3 b(large component mask 7).

As shown in FIG. 6, the controller 80 is mainly constituted by anarithmetic processing portion 81, a storage portion 82, an externalinput/output portion 83, an image processing portion 84, and a motorcontrol portion 85. The controller 80 is connected to a display unit 86and an input device 87. The arithmetic processing portion 81 is anexample of the “control portion” in the present disclosure.

The arithmetic processing portion 81 includes a CPU and generallycontrols the operation of the printing apparatus 100. The storageportion 82 includes an operation program storage portion 82 a storing acontrol program etc. capable of being executed by the arithmeticprocessing portion 81 and a control data storage portion 82 b storingdata required when a printing operation is performed.

The external input/output portion 83 has a function of controlling inputfrom/output to various sensors and actuators. The image processingportion 84 performs processing on image data imaged by the boardrecognition cameras 15 and the mask recognition cameras 24 andinternally generates data required for the operation of the printingapparatus 100.

The motor control portion 85 is configured to control variousservomotors (a servomotor 13 a (13 b) (see FIG. 1) moving the boardworking table 2 a (2 b) in the direction Y, servomotors (not shown) ofthe X-axis movement mechanisms 51 moving the clamp units 23 in thedirection X, the Y-axis motors 33 c of the printing tables 3 a and 3 b,Z-axis motors (not shown) for the mask lift mechanisms 32, etc. of theprinting apparatus 100 on the basis of a control signal output from thearithmetic processing portion 81. The motor control portion 85 isconfigured to be capable of recognizing the position coordinates of theboard working tables 2 a and 2 b along the Y-axis, the positions of theclamp units 23 in the X-Y plane, the position coordinates along theY-axis, the height positions (in the direction Z), and the rotationpositions (the rotation angles in the X-Y plane) of the printing tables3 a and 3 b, etc. on the basis of signals from encoders (not shown) thatthe servomotors have.

According to the first embodiment, the controller 80 (arithmeticprocessing portion 81) is configured to perform control of performing asolder printing operation on the single board 5 by performing secondprinting by the printing table 3 b including the large component mask 7for a large component after performing the first printing by theprinting table 3 a including the small component mask 6 for a smallcomponent. In other words, the printing apparatus 100 sequentiallyperforms the first printing by the printing table 3 a and the secondprinting by the printing table 3 b after the first printing on thesingle board 5.

Operation control in the printing apparatus 100 according to the firstembodiment of the present disclosure during a board printing operationis now described with reference to FIGS. 4, 5, and 7 to 10. A printingoperation performed on the board 5 carried into the board working table2 a is described below as an example of a printing operation. Thefollowing control processing is performed by the controller 80(arithmetic processing portion 81).

As shown in FIGS. 7 and 8, the arithmetic processing portion 81 alignsthe Y-coordinate of the board working table 2 a with the carry-inposition En1 and carries the board 5 onto the conveying conveyor 22 atstep S1. After the board 5 is carried onto the conveying conveyor 22,the board 5 is clamped (fixed) by the clamp unit 23 at step S2.

At step S3, the clamp unit 23 of the board working table 2 a starts tomove in the direction X to the printing table 3 a while the boardworking table 2 a starts to move in the direction Y, and the movement inthe direction X of the clamp unit 23 holding the board 5 and themovement in the direction Y of the board working table 2 a aresynchronously performed. During this movement, the board recognitionmarks (not shown) of the board 5 are located below the board recognitioncamera 15, and the board recognition marks of the board 5 are imaged(the image is recognized) by the board recognition camera 15.

At step S4, the mask recognition camera 24 of the clamp unit 23 of theboard working table 2 a is located below the mask recognition marks Q ofthe small component mask 6 of the printing table 3 a, and the maskrecognition marks Q are imaged (the image is recognized) by the maskrecognition camera 24. Due to the image recognition at steps S3 and S4,the relative positional relationship between the position and posture inthe horizontal direction of the board 5 held by the clamp unit 23 andthe position and posture in the horizontal direction of the smallcomponent mask 6 mounted on the printing table 3 a is acquired.

At step S5, the board 5 held by the clamp unit 23 and the smallcomponent mask 6 held by the printing table 3 a are moved to a printingposition. In other words, on the basis of the results of the recognitionat steps S3 and S4, the position coordinates of the board 5 and thesmall component mask 6 in the direction X are aligned by the movement ofthe clamp unit 23 in the direction X, and the position coordinates ofthe board 5 and the small component mask 6 in the direction Y arealigned by the movement of the board working table 2 a in the directionY and the movement of the printing table 3 a in the direction Y, asshown in FIG. 9. Furthermore, the mask fixing member 31 of the printingtable 3 a is rotated in the horizontal plane (X-Y plane), whereby theinclination of the board 5 and the inclination of the small componentmask 6 in the horizontal plane are matched.

At step S6, the printing table 3 a lowers the small component mask 6 andregisters the small component mask 6 to the board 5 (see FIG. 4). Thus,the small component mask 6 is pressed against the board 5 by prescribedpressing force and is brought into close contact with the board 5. Afterthe completion of the plate register, the first printing is performed bythe small component mask 6 of the printing table 3 a at step S7. Inother words, solder is supplied onto the small component mask 6, and thesqueegee unit 4 a (movable beam 42) is driven (performs a scrapingoperation) in the direction Y in a state where the squeegee 41 islowered and presses the board 5 through the small component mask 6,whereby solder is printed on the upper surface of the board 5 throughthe small component mask 6, and the squeegee 41 is raised. Due to thefirst printing, the solder Sd1 having the solder height H1 is formed atpositions on the board 5 according to the opening pattern of the smallcomponent mask 6. After the first printing, the printing table 3 a israised along arrow Z1, and the small component mask 6 is released fromthe board 5 at step S8.

From step S9, the second printing is performed by the large componentmask 7 of the printing table 3 b. The operations are basically similarto the aforementioned operations at steps S4 to S8, and hence thedescription is simplified. At step S9, the mask recognition marks Q ofthe large component mask 7 of the printing table 3 b are imaged (theimage is recognized) by the mask recognition camera 24 of the clamp unit23. Due to the image recognition at steps S3 and S10, the relativepositional relationship between the position and posture in thehorizontal direction of the board 5 held by the clamp unit 23 and theposition and posture in the horizontal direction of the large componentmask 7 mounted on the printing table 3 b is acquired.

At step S10, the board 5 held by the clamp unit 23 and the largecomponent mask 7 held by the printing table 3 b are moved to a printingposition. In other words, on the basis of the results of the recognitionat steps S3 and S10, the relative positions and postures of the board 5and the large component mask 7 in the horizontal plane are matched bythe movement of the clamp unit 23 in the direction X, the movement ofthe board working table 2 a and the printing table 3 b in the directionY, and the rotation of the mask fixing member 31 of the printing table 3b are aligned by the movement of the board working table 2 a in thedirection Y and the movement of the printing table 3 a in the directionY, as shown in FIG. 10.

At step S11, the printing table 3 b lowers the large component mask 7and registers the large component mask 7 to the board 5 (see FIG. 5).After completion of the plate register, the second printing is performedby the large component mask 7 of the printing table 3 b and the squeegeeunit 4 b at step S12. Thus, the solder Sd2 having the solder height H2is formed at positions on the board 5 according to the opening patternof the large component mask 7 to be added on the board 5 after thesolder Sd1 is formed on the board 5 by the first printing. After thesecond printing, the large component mask 7 is released from the board 5at step S13.

At step S14, clamping (fixing) of the board 5 by the clamp unit 23 isreleased. In other words, the board 5 is arranged on the conveyingconveyor 22 by the support mechanism 53 and the clamp mechanism 52 (seeFIG. 3). The board working table 2 a moves along arrow Y2 to thecarry-out position Ex1. At step S15, the printed board 5 is carried outof the board working table 2 a (conveying conveyor 22) at the carry-outposition Ex1.

According to the first embodiment, as hereinabove described, theprinting table 3 a holds the small component mask 6 having the firstthickness Th1 that is a prescribed thickness configured to perform thefirst printing of printing solder on the board 5. The printing table 3 bholds the large component mask 7 formed with the relief portion 7 bhaving the depth D larger than the first thickness Th1 on the boardcontact surface to relieve the solder Sd1 having the solder height H1printed by the small component mask 6, having the second thickness Th2that is a prescribed thickness thicker than the first thickness Th1 toperform the second printing of printing solder on the board 5 after thefirst printing by the printing table 3 a. The arithmetic processingportion 81 is configured to perform the second printing by the largecomponent mask 7 of the printing table 3 b after the first printing bythe small component mask 6 of the printing table 3 a is performed on theboard 5 held by the board working table 2 a (2 b). Thus, the firstprinting using the small component mask (very small component mask) 6and the second printing using the large component mask 7 can beperformed by the single printing apparatus 100. Thus, it is notnecessary to provide two board printing apparatuses in the productionline, and hence the board can be produced without complicating thestructure of the production line even in the case where printing isperformed using two types of masks, the small component mask 6 and thelarge component mask 7.

Second Embodiment

A printing apparatus 100 a according to a second embodiment of thepresent disclosure is now described with reference to FIGS. 6, 7, and 12to 14. In this second embodiment, an example of performing the printingpreparation operation of one of printing tables 3 a and 3 b during theprinting operation of the other of the printing tables 3 a and 3 b inaddition to the aforementioned structure of the printing apparatus 100according to the first embodiment is described.

An arithmetic processing portion 81 a (see FIG. 6) of the printingapparatus 100 a according to the second embodiment is configured toperform the printing preparation operation of one of the printing table3 a and the printing table 3 b during the board printing operation ofthe other of the printing table 3 a and the printing table 3 b. Thearithmetic processing portion 81 a is an example of the “controlportion” in the present disclosure.

In other words, in the board printing operation performed by theprinting apparatus 100 a, first printing by the printing table 3 a andsecond printing by the printing table 3 b are sequentially performed, sothat a standby period T1 (standby processing) is generated in theprinting table 3 b during the printing operation of the printing table 3a, for example, as shown in FIG. 7. The printing preparation operationis performed in advance during this standby period T1, whereby thearithmetic processing portion 81 a reduces the time required forprocessing (at steps S9 to S13) for the second printing by the printingtable 3 b. The board printing operation includes at least operationsfrom the start of movement to a printing position (steps S5 and S10) tothe termination of plate releasing (steps S8 and S13). The mask markrecognition at steps S4 and S9 is not necessarily performed each timewhen the printing operation is continuously performed. Therefore, whenthe mask mark recognition is performed, this mask mark recognitionoperation is also included in the printing operation.

Specifically, according to the second embodiment, the arithmeticprocessing portion 81 a is configured to perform control (advanceapproach operation) of moving the printing table 3 b closer to theprinting position by moving the printing table 3 b in a direction Y suchthat a distance between the printing table 3 a and the printing table 3b in the direction Y is reduced during the board printing operation ofthe printing table 3 a. This corresponds to performing in advance partof processing for movement to the printing position at the step S10 inFIG. 7.

The advance approach operation is now described. As shown in FIG. 12,the Y-axis of the printing table 3 a is shown by (Y_(M1)), and theY-axis of the printing table 3 b is shown by (Y_(M2)). As to the Y-axiscoordinates, the positions of the outer ends in the direction Y in thecase where the printing tables 3 a and 3 b are located on the outer endsof movement ranges in the direction Y are set to original points, and adirection in which the printing tables 3 a and 3 b come closer to eachother is set to be positive. For ease of description, the positioncoordinates of the inner ends of the printing tables 3 a and 3 b in thedirection Y are used as the positions of the printing tables 3 a and 3b.

The distance between the printing tables 3 a and 3 b in a state wherethe printing tables 3 a and 3 b are closest to each other withoutinterference is calculated from an actual measured or design value andis set to an accessible minimum interval L_(m).

Assuming that the Y-direction coordinates of the printing table 3 a andthe printing table 3 b are Y_(1m) and Y_(2m), respectively when theprinting table 3 a and the printing table 3 b are moved such that thedistance between the printing tables is the minimum interval L_(m), adistance L_(i) between the original points of the Y-axis can beexpressed as follows:

L _(i) =L _(m) +Y _(1m) +Y _(2m)

Assuming that the current position coordinate of the printing table 3 aduring the board printing operation (first printing) is Y_(AC) and thetarget position coordinate of the printing table 3 b moved closer isY_(BN), the target position coordinate Y_(BN) can be expressed asfollows:

Y _(BN) =L ₁ −L _(m) −Y _(AC)

Thus, during the board printing operation of the printing table 3 a, theprinting table 3 b can be moved to the closest position coordinate(target position coordinate Y_(BN)) without interference. According tothe second embodiment, these minimum interval L_(m) and distance L_(i)between the original points are previously acquired and stored in acontrol data storage portion 82 b. The current position coordinateY_(AC) of the printing table 3 a is acquired from the encoder outputvalue of a Y-axis motor 33 c of a mask drive mechanism 33 of theprinting table 3 a.

In the printing apparatus 100 a according to the second embodiment, thearithmetic processing portion 81 a performs the advance approachoperation of the printing table 3 b at a prescribed time point duringthe steps S4 to S8 (standby period T1) in FIG. 7. Thus, during the boardprinting operation (first printing) of the printing table 3 a, theprinting table 3 b is moved (approaches) along arrow Y2 to a position(target position coordinate Y_(BN)) where an interval between theprinting table 3 a and the printing table 3 b is the minimum intervalL_(m), as shown in FIG. 13.

After the shift to step S9 in FIG. 7, the printing tables 3 a and 3 bmove along arrow Y2 while keeping a distance equal to or more than theminimum interval L_(m) following the movement of a board working table 2a along arrow Y1, as shown in FIG. 14. Consequently, the time requiredfor the movement to the printing position at the step S10 (the movementdistance in the direction Y) is minimized.

The remaining structure of the printing apparatus 100 a according to thesecond embodiment is similar to that of the aforementioned printingapparatus 100 according to the first embodiment, and hence thedescription is omitted.

According to the second embodiment, as hereinabove described, thearithmetic processing portion 81 a performs the printing preparationoperation of the printing table 3 b during the board printing operationof the printing table 3 a. Thus, the preparation operation forsubsequent printing can be performed in advance in the printing table 3b, utilizing the standby period during the board printing operation(first printing) of the printing table 3 a. Consequently, the timerequired for board printing (the time required for the board printingoperation and the printing preparation operation) can be reduced even inthe case where the first printing and the second printing are performedby the single printing apparatus 100 a.

According to the second embodiment, as hereinabove described, thearithmetic processing portion 81 a moves the printing table 3 b closerto the printing position by moving the printing table 3 b along arrow Y2such that the distance between the printing table 3 a and the printingtable 3 b in the direction Y is reduced during the board printingoperation (first printing) of the printing table 3 a. Thus, part of theoperation of the movement of the printing table 3 b to the printingposition can be performed during the board printing operation (firstprinting) of the printing table 3 a, and hence the time required forboard printing (the movement time to the printing position) can bereduced when the second printing is performed by the printing table 3 b.

According to the second embodiment, as hereinabove described, theprinting table 3 b is moved closer to the printing position until theinterval between the printing tables 3 a and 3 b becomes the accessibleminimum interval L_(m) without interference during the board printingoperation of the printing table 3 a. Thus, the printing table 3 b can bemoved as close as possible to the printing position during the boardprinting operation of the printing table 3 a, and hence the timerequired for board printing can be effectively reduced when the secondprinting is performed by the printing table 3 b.

According to the second embodiment, as hereinabove described, theprinting table 3 b is located at the printing position by moving theprinting table 3 a and the printing table 3 b along arrow Y2 while thedistance equal to or more than the minimum interval L_(m) is kept whenthe second printing is performed by the printing table 3 b after theprinting table 3 b is moved closer to the printing position. Thus, thetime required for the movement of the printing table 3 b to the printingposition can be reduced, as compared with the case where the printingtable 3 a and the printing table 3 b are moved in order (individually).

The remaining effects of the second embodiment are similar to those ofthe aforementioned first embodiment.

Third Embodiment

A printing apparatus 100 b according to a third embodiment of thepresent disclosure is now described with reference to FIGS. 6, 7, and15. In this third embodiment, another example of performing the printingpreparation operation of one of printing tables 3 a and 3 b during theprinting operation of the other of the printing tables 3 a and 3 b,different from the aforementioned example of the second embodiment, isdescribed.

An arithmetic processing portion 81 b (see FIG. 6) of the printingapparatus 100 b according to the third embodiment is configured toperform control (advance lowering operation) of lowering a mask fixingmember 31 (large component mask 7) of the printing table 3 b from aplate releasing height position H3 (see FIG. 15) after second printingto a standby height position H4 (see FIG. 15) lower than the platereleasing height position H3, where solder Sd1 on a board 5 is not incontact with the large component mask 7 during the board printingoperation (first printing) of the printing table 3 a. This correspondsto performing in advance part of the plate registering operation at stepS11 in FIG. 7. The plate releasing height position H3 is an example ofthe “large component mask plate releasing height position” in thepresent disclosure. The arithmetic processing portion 81 b is an exampleof the “control portion” in the present disclosure.

The height position of the printing table (mask) at the time of platereleasing is now described. The plate releasing height position isdetermined by the solder height of solder formed by printing and theamount of deflection of the mask, and a safety margin for ensuring thatthe mask does not contact the formed solder.

In the case of the large component mask 7 (printing table 3 b), when thesolder height of solder Sd2 (the maximum height of the solder on theboard 5) is H2, the amount of deflection of the large component mask 7is ΔH, and the safety margin is H_(m), using a printing height (heightposition at the time of the plate register) H0 as a reference, as shownin FIG. 15, the plate releasing height position H3 after the secondprinting is expressed as follows:

H3=H2+ΔH+H _(m)

The solder Sd2 is not formed on the board 5 before the second printingby the large component mask 7 (printing table 3 b), and only the solderSd1 having a solder height H1 (i.e. the thickness Th1 of a smallcomponent mask 6) is formed. Therefore, before the second printing, theprinting table 3 b (large component mask 7) can be lowered to thestandby height position H4 shown in the following expression while thesolder Sd1 on the board 5 is not in contact with the large componentmask 7.

H4=H1+ΔH+H _(m)

In other words, before the second printing, the large component mask 7can be lowered by a distance corresponding to a difference between thesolder height H1 before the second printing and the maximum solderheight H2 after the second printing.

Thus, the printing table 3 b is lowered to the standby height positionH4 where the printing table 3 b does not interfere with the solder Sd1on the board 5 during the board printing operation (first printing) ofthe printing table 3 a.

The solder height H1 corresponds to the thickness (first thickness) Th1of the small component mask 6, so that the solder height H1 ispreviously stored as part of the board data of the board 5 to beproduced in a control data storage portion 82 b. The safety margin H_(m)is a prescribed value previously set in the control data storage portion82 b. The amount of deflection ΔH of the mask mainly depends on thedimension (length, width, and thickness) of the mask. Therefore,according to the third embodiment, a table associating the dimension ofthe mask with the amount of dimensional deflection ΔH is previouslyprepared and stored in the control data storage portion 82 b. Thearithmetic processing portion 81 b is configured to acquire the amountof deflection ΔH corresponding to the dimension of the large componentmask 7 registered in the board data from the control data storageportion 82 b.

In the printing apparatus 100 b according to the third embodiment, thearithmetic processing portion 81 b performs the advance loweringoperation of the printing table 3 b at a prescribed time point duringthe steps S4 to S8 (standby period T1) in FIG. 7. Thus, during the boardprinting operation (first printing) of the printing table 3 a, the largecomponent mask 7 of the printing table 3 b is previously lowered fromthe plate releasing height position H3 to the standby height positionH4, as shown in FIG. 15.

When the large component mask 7 is registered to the board 5 at step S11in FIG. 7, the printing table 3 b (large component mask 7) is loweredfrom the standby height position H4 lower than the plate releasingheight position H3 to the printing height H0, and the large componentmask 7 is registered to the board 5. Consequently, the time required toregister the large component mask 7 to the board 5 at step S11 (themovement distance in a direction Z) is minimized.

The remaining structure of the printing apparatus 100 b according to thethird embodiment is similar to that of the aforementioned printingapparatus 100 according to the first embodiment, and hence thedescription is omitted.

According to the third embodiment, as hereinabove described, thearithmetic processing portion 81 b lowers the printing table 3 b fromthe plate releasing height position H3 with respect to the board 5 afterthe second printing to the standby height position H4 lower than theplate releasing height position H3, where the solder Sd1 having thesolder height H1 on the board 5 is not in contact with the largecomponent mask 7 during the board printing operation (first printing)using the small component mask 6 of the printing table 3 a. Thus, duringthe board printing operation (first printing) of the printing table 3 a,the printing table 3 b can perform in advance part of the loweringoperation for registering the large component mask 7 to the board 5 inthe printing table 3 b. Consequently, the time required for boardprinting can be reduced when the second printing is performed by theprinting table 3 b.

In the case of continuous production of the board 5, after carrying theboard 5 out of the conveying conveyor 22 at step S15 in FIG. 7, thearithmetic processing portion 81 b returns to step S1 and carries a newboard 5 into the conveying conveyor 22. Therefore, the advance loweringoperation may be performed on a subsequent board 5 in the printing table3 a during a standby period T2 (steps S9 to S13) after the firstprinting performed on a prior board 5. In this case, no solder is formedon the board 5 before the first printing is carried into the conveyingconveyor 22 (the solder height is 0), and hence the printing table 3 acan be lowered in advance to the standby height position (not shown)corresponding to the amount of deflection ΔH+the safety margin Hmaccording to the dimension of the small component mask 6.

According to the third embodiment, as hereinabove described, the standbyheight position H4 is determined on the basis of at least the thicknessTh1 (i.e. solder height H1) of the small component mask 6 and the amountof deflection ΔH of the large component mask 7. Thus, the largecomponent mask 7 can be arranged at the standby height position H4 wherethe large component mask 7 is moved as close as possible to the board 5after the first printing in consideration of the thickness Th1corresponding to the height H1 of the solder Sd1 formed on the board 5after the first printing and the amount of deflection ΔH of the largecomponent mask 7 for performing the second printing. Thus, the timerequired for board printing can be effectively reduced when the secondprinting is performed by the printing table 3 b.

The remaining effects of the third embodiment are similar to those ofthe aforementioned second embodiment.

Fourth Embodiment

A printing apparatus 100 c according to a fourth embodiment of thepresent disclosure is now described with reference to FIGS. 6, 7, 12,and 16. In this fourth embodiment, another example of performing theprinting preparation operation of one of printing tables 3 a and 3 bduring the printing operation of the other of the printing tables 3 aand 3 b, different from the aforementioned example of the thirdembodiment, is described.

An arithmetic processing portion 81 c (see FIG. 6) of the printingapparatus 100 c according to the fourth embodiment is configured toperform control (advance mask recognition) of recognizing a largecomponent mask 7 of the printing table 3 b using a board working table 2b during the board printing operation (first printing) of a boardworking table 2 a and the printing table 3 a. This corresponds toperforming in advance mask mark recognition at step S9 in FIG. 7. Thearithmetic processing portion 81 c is an example of the “controlportion” in the present disclosure.

Specifically, the arithmetic processing portion 81 c moves the printingtable 3 b along arrow Y1 during the board printing operation (firstprinting) of the board working table 2 a and the printing table 3 a, asshown in FIG. 16. Then, the arithmetic processing portion 81 c locates amask recognition camera 24 of a clamp unit 23 below mask recognitionmarks Q of the large component mask 7 of the printing table 3 b by themovement in a direction Y of the board working table 2 b in a standbystate and the movement in a direction X of the clamp unit 23 of theboard working table 2 b and images (recognizes the image of) the maskrecognition marks Q by the mask recognition camera 24. Thus, theposition and posture of the large component mask 7 in a horizontaldirection are recognized.

When performing the advance mask recognition, the arithmetic processingportion 81 c performs the mask mark recognition (at the step S9) of thelarge component mask 7 by the mask recognition camera 24 of anotherboard working table 2 b in the case where second printing is performedon the board 5 held by the board working table 2 a. Therefore, accordingto the fourth embodiment, the arithmetic processing portion 81 cperforms processing for adjusting the relative positions of thecoordinate system (the X-axis and the Y_(M1)-axis (see FIG. 12)) in thehorizontal direction of the mask recognition camera 24 of the boardworking table 2 a and the coordinate system (the X-axis and theY_(M2)-axis (see FIG. 12)) in the horizontal direction of the maskrecognition camera 24 of the board working table 2 b recognizing thelarge component mask 7.

Specifically, the relative positional relationship (positionaldisplacement between both coordinates in the direction X and thedirection Y) between the coordinate system of the mask recognitioncamera 24 of the board working table 2 a and the coordinate system inthe horizontal direction of the mask recognition camera 24 of the boardworking table 2 b recognizing the large component mask 7 is previouslymeasured, and correction parameters for converting each other'scoordinate systems are prepared and stored in a control data storageportion 82 b. Thus, the arithmetic processing portion 81 c can convertthe position coordinates of the large component mask 7 acquired with themask recognition camera 24 of the board working table 2 b into thecoordinate system (the X-axis and the Y_(M1)-axis) of the maskrecognition camera 24 of the board working table 2 a with the correctionparameters to use the same.

In the printing apparatus 100 c according to the fourth embodiment, thearithmetic processing portion 81 c performs the advance mask recognitionof the printing table 3 b at a prescribed time point during steps S4 toS8 (standby period T1) in FIG. 7. Thus, the mask mark recognition atstep S9 in FIG. 7 is completed during steps S4 to S8. When step S8 iscompleted, therefore, the arithmetic processing portion 81 c skips thealready completed step S9 and advances to step S10. At step S10, thearithmetic processing portion 81 c performs processing for moving theboard working table 2 a and the printing table 3 b to a printingposition by associating the horizontal position of the board 5 with thehorizontal position of the large component mask 7, using the recognitionresult of board marks at step S3, the recognition result acquired by theadvance mask recognition, and the correction parameter previously storedin the control data storage portion 82 b.

The remaining structure of the printing apparatus 100 c according to thefourth embodiment is similar to that of the aforementioned printingapparatus 100 according to the first embodiment, and hence thedescription is omitted.

According to the fourth embodiment, as hereinabove described, thearithmetic processing portion 81 c recognizes the large component mask 7of the printing table 3 b using the board working table 2 b during theboard printing operation of the board working table 2 a and the printingtable 3 a using the small component mask 6. Thus, the mask recognitionfor aligning the large component mask 7 with the board 5 can beperformed in advance in the printing table 3 b during the board printingoperation (first printing) of the printing table 3 a using the smallcomponent mask 6. Consequently, the arithmetic processing portion 81 ccan skip step S9 in FIG. 7 and directly perform the second printing bythe large component mask 7 that has been already recognized after thefirst printing, and hence the time required for board printing can bereduced when the second printing is performed.

The mask recognition is required to relatively align the masks with theboards (the board working tables 2 a and 2 b), and hence the maskrecognition must be performed at least at the time of the initialprinting of the printing apparatus. On the other hand, the mask is fixedto a mask fixing member 31 of the printing table 3 a (3 b), so that maskrecognition is not necessarily required each time the printing operationis performed. However, minute positional displacement is generated dueto the thermal extension or the like of each part such as a ball screwshaft of a drive mechanism also during the operation of the apparatus,and hence the mask recognition may be regularly performed each time acertain number of boards are produced or each time a certain period oftime elapses, for example.

According to the fourth embodiment, as hereinabove described, thearithmetic processing portion 81 c recognizes the large component mask 7using the board working table 2 b at least when the board printingoperation is first performed by the board working table 2 a and theprinting table 3 a. Thus, at least the first mask recognition operationis performed in advance, whereby the second printing can be immediatelystarted. If mask recognition is performed at least when the printing isfirst performed, the subsequent mask recognition can be skipped byutilizing the mask recognition result.

The remaining effects of the fourth embodiment are similar to those ofthe aforementioned second embodiment.

Fifth Embodiment

A printing apparatus 100 d according to a fifth embodiment of thepresent disclosure is now described with reference to FIGS. 6, 7, 9, 10,17, and 18. In this fifth embodiment, another example of performing theprinting preparation operation of one of printing tables 3 a and 3 bduring the printing operation of the other of the printing tables 3 aand 3 b, different from the aforementioned example of the fourthembodiment, is described.

An arithmetic processing portion 81 d (see FIG. 6) of the printingapparatus 100 d according to the fifth embodiment is configured toperform control (advance cleaning operation) of cleaning a smallcomponent mask 6 of the printing table 3 a with the board working table2 a during the board printing operation (second printing) of a boardworking table 2 b and the printing table 3 b on a board 5 after firstprinting. This is not shown in FIG. 7 but corresponds to performing inadvance a mask cleaning operation between board printing and subsequentboard printing (after the step S15 in FIG. 7 is completed and before asubsequent board 5 is carried into the conveying conveyor 22). Thearithmetic processing portion 81 d is an example of the “controlportion” in the present disclosure.

In an advance processing operation of performing the printingpreparation operation of one of the printing tables 3 a and 3 b duringthe printing operation of the other of the printing tables 3 a and 3 b,it is necessary to arrange the board working table (2 a or 2 b) in astandby state not performing the board printing operation and theprinting table (3 a or 3 b) in a standby state on the same side of theprinting apparatus in the direction Y in the case where the advanceprocessing is performed with the board working table 2 a (2 b) (in thecase of the aforementioned fourth or fifth embodiment).

In other words, the printing preparation operation performed by allowingthe board working table 2 b and the printing table 3 b to cooperate witheach other can be performed in advance when both the board working table2 b and the printing table 3 b on the Y1 side are in a standby state, asshown in FIG. 9, for example. On the other hand, when the board workingtable 2 b on the Y1 side and the printing table 3 a on the Y2 side arein a standby state, as shown in FIG. 10, the printing operation (thesecond printing performed by the board working table 2 a and theprinting table 3 b) is performed between the board working table 2 b andthe printing table 3 a, and hence the board working table 2 b cannot bemoved in the direction Y to the printing table 3 a.

In the fifth embodiment, an example of performing the advance cleaningoperation for the small component mask 6 of the printing table 3 a withthe board working table 2 a while the board working table 2 b and theprinting table 3 b perform in advance the board printing operation(second printing) is described as an example of performing the maskcleaning operation.

As shown in FIG. 17, also according to the fifth embodiment, the boardprinting processing at steps S1 to S15 shown in FIG. 7 is performed inthe board working table 2 b. The processing flow in FIG. 17 is preparedas the middle of the printing operation continuously performed, and themask recognition processing at steps S4 and S9 is omitted.

In the case of FIG. 17, the board working table 2 a and the printingtable 3 b are in a standby state at steps S5 to S8 (first printing).When plate release processing at step S8 is terminated, the processingflow moves to the second printing (at steps S10 to S13) performed by theboard working table 2 a and the printing table 3 b, and both the boardworking table 2 a and the printing table 3 a of the printing apparatus100 d on the Y2 side are in a standby state. Thus, the advance cleaningoperation performed by allowing the board working table 2 a and theprinting table 3 a to cooperate with each other can be performed.

According to the fifth embodiment, the arithmetic processing portion 81d moves the printing table 3 a along arrow Y2 in a direction separatingfrom the printing table 3 b during the second printing (at steps S10 toS13), as shown in FIG. 18. Then, the arithmetic processing portion 81 drelatively moves the board working table 2 a and the small componentmask 6 (printing table 3 a) in the direction Y while raising an unshowncleaning head of a cleaning unit 25 of the board working table 2 a andbringing the cleaning head into contact with the board contact surfaceof the small component mask 6, thereby sliding the cleaning head in thedirection Y with respect to the small component mask 6. At this time,the cleaning head removes solder paste by suctioning the same undernegative pressure by an unshown suction nozzle. Thus, the board contactsurface of the small component mask 6 is cleaned. Consequently, the maskcleaning operation generally performed between board printing andsubsequent board printing is completed during steps S10 to S13.Therefore, after the completion of the board printing at step S15, thearithmetic processing portion 81 d can skip the mask cleaning operationperformed in advance and perform the printing operation of a subsequentboard 5 in the printing table 3 a (small component mask 6).

The remaining structure of the printing apparatus 100 d according to thefifth embodiment is similar to that of the aforementioned printingapparatus 100 according to the first embodiment, and hence thedescription is omitted.

According to the fifth embodiment, as hereinabove described, thearithmetic processing portion 81 d performs the mask cleaning operationfor the small component mask 6 of the printing table 3 a using the boardworking table 2 a while the board working table 2 b and the printingtable 3 b perform the board printing operation (second printing) on theboard 5 after the first printing with the large component mask 7. Thus,the mask cleaning operation for the small component mask 6 can beperformed in the printing table 3 a during the board printing operation(second printing) of the printing table 3 b after the board printing(first printing) of the printing table 3 a. Consequently, the timerequired for the printing preparation operation can be reduced when thefirst printing is performed on the subsequent board 5 by the printingtable 3 a.

In the advance cleaning operation according to the fifth embodiment, itis simply required to arrange the board working table (2 a or 2 b) in astandby state and the printing table (3 a or 3 b) in a standby state onthe same side in the direction Y, as described above, and hence the maskcleaning operation for the large component mask 7 of the printing table3 b may be performed using the board working table 2 b while the boardworking table 2 a and the printing table 3 a perform the board printingoperation (first printing).

According to the fifth embodiment, as hereinabove described, thearithmetic processing portion 81 d moves the printing table 3 a alongarrow Y2 in the direction separating from the printing table 3 b andperforms the mask cleaning operation for the small component mask 6 at aposition separating from the printing table 3 b while the board workingtable 2 b and the printing table 3 b perform the board printingoperation (second printing). Thus, the printing table 3 a can beseparated from the printing table 3 b during the mask cleaningoperation, and hence a work space for the mask cleaning operation can beensured during the second printing performed by the printing table 3 b.

The remaining effects of the fifth embodiment are similar to those ofthe aforementioned second embodiment.

Sixth Embodiment

A printing apparatus 100 e according to a sixth embodiment of thepresent disclosure is now described with reference to FIGS. 6 to 10 and19 to 23. In this sixth embodiment, an example of performing theprinting operation of one of printing tables 3 a and 3 b during theprinting operation of the other of the printing tables 3 a and 3 b,different from the aforementioned examples of the second to fifthembodiments in which the printing preparation operation of one of theprinting tables 3 a and 3 b is performed during the printing operationof the other of the printing tables 3 a and 3 b, is described.

The printing apparatus 100 e (see FIG. 21) according to the sixthembodiment is configured to alternately carry a board 5 into a boardworking table 2 a and a board working table 2 b and perform printing.

An arithmetic processing portion 81 e (see FIG. 6) of the printingapparatus 100 e according to the sixth embodiment is configured toperform control of performing a board printing operation (firstprinting) on a second board 5 before first printing by the printingtable 3 a and one of the board working tables 2 a and 2 b during a boardprinting operation (second printing) performed on a first board 5 afterthe first printing by the printing table 3 b and the other of the boardworking tables 2 a and 2 b. The arithmetic processing portion 81 e is anexample of the “control portion” in the present disclosure.

The arithmetic processing portion 81 e of the printing apparatus 100 eaccording to the sixth embodiment is configured to perform control ofcarrying the board 5 into one of the board working tables 2 a and 2 band carrying the board 5 out of one of the board working tables 2 a and2 b during the board printing operation performed by one of the printingtables 3 a and 3 b and the other of the board working tables 2 a and 2b.

The remaining structure of the printing apparatus 100 e according to thesixth embodiment is similar to that of the aforementioned printingapparatus 100 according to the first embodiment, and hence thedescription is omitted.

Board printing operation processing performed by the printing apparatus100 e according to the sixth embodiment is now described with referenceto FIGS. 6 to 10 and 19 to 23. The following processing is controlled bythe arithmetic processing portion 81 e of the printing apparatus 100 e.

In the board printing operation processing performed by the printingapparatus 100 e according to the sixth embodiment, printing processingperformed on the individual board 5 is basically similar to theprocessing at steps S1 to S15 in FIG. 7. As to the board 5, the numberof the boards is indicated below by a, b, c, and d. The first is termeda board 5 a, the second is termed a board 5 b, the third is termed aboard 5 c, and the fourth is termed a board 5 d. An example ofterminating a printing operation by performing printing on the fourboards 5 is shown for descriptive purposes. In FIGS. 19 and 20, the maskrecognition at steps S4 and S9 in FIG. 7 is performed only at the timeof initial printing, and the mask recognition is omitted at the time ofprinting on the subsequent boards 5 (5 b to 5 d). The alphabets a, b, c,and d attached to the ends of steps indicate processing on the board 5a, the board 5 b, the board 5 c, and the board 5 d. In this example, theboard 5 (5 a) is first carried into the board working table 2 a.

As shown in FIG. 19, first, the board 5 (5 a) is carried into the boardworking table 2 a through a carry-in position En1 (see FIG. 8) at stepS1 a. Through board fixing at step S2 a and board mark recognition atstep S3 a, a small component mask 6 of the printing table 3 a isrecognized (only for the first time) at step S4 a.

Next, at steps S5 a to S8 a, the first printing is performed on theboard 5 a by the board working table 2 a and the printing table 3 a.After the small component mask 6 is released from the board 5 a at stepS8 a, a large component mask 7 of the printing table 3 b is recognized(only for the first time) at step S9 a.

Then, at steps S10 a to S13 a, the second printing (see FIG. 10) isperformed on the board 5 a by the board working table 2 a and theprinting table 3 b. Meanwhile, in the board working table 2 b, the board5 (5 b) is carried into the board working table 2 b through a carry-inposition Ent at step S1 b, and board fixing at step S2 b and board markrecognition (see FIG. 23) at step S3 b are performed.

After the large component mask 7 is released from the board 5 a at stepS13 a, fixing of the board 5 a on the board working table 2 a isreleased, and the board working table 2 a moves along arrow Y2 to acarry-out position Ex1 at step S14 a. As shown in FIG. 21, the board 5 ais carried out of the board working table 2 a through the carry-outposition Ex1 at step S15 a, the processing advances to step S1 c (seeFIG. 19), the board 5 (5 c) is carried into the board working table 2 athrough the carry-in position En1, and the board 5 c is fixed at step S2c.

After the large component mask 7 is released from the board 5 a at stepS13 a, the board working table 2 a moves along arrow Y2 to the carry-outposition Ex1, and hence the board working table 2 b becomes movablealong arrow Y2 to the printing table 3 a. During steps S14 a to S2 c,the first printing (steps S5 b to S8 b) is performed on the board 5 b bythe board working table 2 b and the printing table 3 a in the boardworking table 2 b, as shown in FIG. 21. In other words, during the boardprinting operation (steps S5 b to S8 b) performed by the board workingtable 2 b and the printing table 3 a, the board 5 a is carried out ofthe board working table 2 a (step S15 a), and the board 5 c is carriedinto the board working table 2 a (step S1 c).

After the small component mask 6 is released from the board 5 b (step S8b), the second printing is performed on the board 5 b by the boardworking table 2 b and the printing table 3 b in the board working table2 b at steps S10 b to S13 b. As shown in FIG. 22, the board workingtable 2 b moves along arrow Y1 to a printing position of the secondprinting while the printing table 3 b moves along arrow Y2 to theprinting position of the second printing at step S10 b, and the secondprinting is performed after the completion of plate register.

Meanwhile, board recognition marks of the board 5 c are recognized (stepS3 c), and thereafter the first printing is concurrently performed onthe board 5 c by the board working table 2 a and the printing table 3 aat step S5 c (movement to a printing position), step S6 c (plateregister), and step S7 c (printing) in the board working table 2 a. Inthis manner, according to the sixth embodiment, the board printingoperation (first printing) (steps S5 c to S7 c) is performed on theboard 5 c by the printing table 3 a and the board working table 2 aduring the board printing operation (second printing) performed on theboard 5 b by the printing table 3 b and the board working table 2 b atsteps S10 b to S13 b.

After the large component mask 7 is released from the board 5 b at thestep S13 b, the board working table 2 b moves from the position shown inFIG. 22 to a carry-out position Ex2 along arrow Y1, and fixing of theboard 5 b is released (step S14 b). Consequently, the board workingtable 2 a becomes movable along arrow Y1 to the printing table 3 b. Inthe board working table 2 a, the small component mask 6 is released fromthe board 5 c at a step S8 c, and thereafter the second printing (stepsS10 c to S13 c) is performed on the board 5 c by the board working table2 a and the printing table 3 b, as shown in FIG. 20. As shown in FIG.23, in parallel with this second printing (steps S10 c to S13 c), theboard 5 b is carried out of the board working table 2 b through thecarry-out position Ex2 (step S15 b), the board 5 d is carried into theboard working table 2 b through the carry-in position Ent (step S1 d),the board 5 d is fixed (step S2 d), and board recognition marks of theboard 5 d are recognized (step S3 d) in the board working table 2 b.

After the large component mask 7 is released from the board 5 c (stepS13 c) in the board working table 2 a, the board working table 2 a movesfrom the position shown in FIG. 23 to the carry-out position Ex1 alongarrow Y2, and fixing of the board 5 c is released (step S14 c). Then,the board 5 c is carried out of the board working table 2 a at thecarry-out position Ex1 (step S15 c), as shown in FIG. 21. Thus, theprinting processing in the board working table 2 a is terminated, andthe board working table 2 a is put in a standby state at the carry-outposition Ex1 (carry-in position En1).

On the other hand, the board working table 2 b moves along arrow Y2 tothe printing position of the printing table 3 a at step S4 d, followingthe movement of the board working table 2 a along arrow Y2 (step S14 c).Then, the first printing is performed on the board 5 d by the boardworking table 2 b and the printing table 3 a at steps S5 d to S8 d whilethe board 5 c is carried out of the board working table 2 a (step S15c), as shown in FIG. 21. Then, the second printing is performed on theboard 5 d by the board working table 2 b and the printing table 3 b atsteps S10 d to S13 d. Thereafter, fixing of the board 5 d is released atstep S14 d, the board working table 2 b moves along arrow Y1 to thecarry-out position Ex2, and the board 5 d is carried out of the boardworking table 2 b through the carry-out position Ex2 at step S15 d.Thus, the printing processing in the board working table 2 b isterminated, the board working table 2 b is put in a standby state at thecarry-out position Ex2 (carry-in position En2), and the printingoperation of the printing apparatus 100 e is terminated.

According to the sixth embodiment, as hereinabove described, thearithmetic processing portion 81 e performs the board printing operation(steps S5 c to S8 c) of the first printing on the board 5 (5 c) beforethe first printing by the printing table 3 a and the board working table2 a during the board printing operation (steps S10 b to S13 b) of thesecond printing performed on the board 5 (5 b) after the first printingby the printing table 3 b and the board working table 2 b. Thus, duringthe second printing performed on the board 5 b (first board), the firstprinting can be performed in advance on the board 5 c (second board) tobe printed on next. Consequently, the time required for the boardprinting operation can be reduced when printing is performed on thesubsequent board 5 c even in the case where the first printing and thesecond printing are performed by the single printing apparatus 100 e.

According to the sixth embodiment, as hereinabove described, thearithmetic processing portion 81 e carries the board 5 into one of theboard working tables 2 a and 2 b (steps S1 b, S1 c, and S1 d) andcarries the board 5 out of one of the board working tables 2 a and 2 b(steps S15 a, S15 b, and S15 c) during the board printing operationperformed by one of the printing tables 3 a and 3 b and the other of theboard working tables 2 a and 2 b. Thus, the board 5 can be carried intoand carried out of one of the board working tables 2 a and 2 b for thesubsequent board printing during the board printing operation performedby the other of the board working tables 2 a and 2 b. Consequently, thetime required for the printing preparation operation (the operation ofcarrying the board into the board working table and the operation ofcarrying the board out of the board working table) can be reduced whenprinting is performed on the subsequent board 5 even in the case wherethe first printing and the second printing are performed by the singleprinting apparatus 100 e.

The remaining effects of the sixth embodiment are similar to those ofthe aforementioned second embodiment.

Modification of Sixth Embodiment

While the arithmetic processing portion 81 e is configured to performcontrol of performing the first printing and the second printing on thedifferent boards 5 concurrently and control of carrying another boardinto and out of the board working table concurrently with the boardprinting operation in the aforementioned sixth embodiment, in additionto this, the control shown in the aforementioned second to fifthembodiments may be performed concurrently.

Specifically, in the flowcharts shown in FIGS. 19 and 20, standbyperiods T4, T5, and T6 and standby periods T7, T8, and T9 exist in theoperation of the printing table 3 a and the operation of the printingtable 3 b, respectively. Therefore, the printing preparation operationscan be performed in advance during these standby periods.

For example, in the printing table 3 a, the advance approach operationshown in the aforementioned second embodiment and the advance loweringoperation shown in the aforementioned third embodiment can be performedfor the first printing during the standby periods T4 and T5. If theadvance approach operation and the advance lowering operation areperformed during the standby period T4, the time required for theprocessing for movement to the printing position at the step S5 bimmediately after the standby period T4 and the processing for plateregister at step S6 b can be reduced. Similarly in the printing table 3b, the advance approach operation and the advance lowering operation canbe performed for the second printing during the standby periods T7, T8,and T9.

During the standby period T7, the board working table 2 b located on thesame side (Y1 side) as the printing table 3 b in the direction Y as wellas the printing table 3 b are put in a standby state. Therefore, duringthe standby period T7, the advance mask recognition shown in theaforementioned fourth embodiment can be performed. In this case, themask mark recognition performed by the board working table 2 a at stepS9 a is performed in advance during the standby period T7 in which themask mark recognition (step S4 a) and the first printing (steps S5 a toS8 a) are performed in the printing table 3 a. Consequently, step S9 acan be skipped. During the standby period T6, the board working table 2a located on the same side (Y2 side) as the printing table 3 a in thedirection Y as well as the printing table 3 a are put in a standby stateafter the termination of board printing. Therefore, during the standbyperiod T6, the advance cleaning operation shown in the aforementionedfifth embodiment can be performed. Thus, during the second printing(steps S10 d to S13 d) performed by the printing table 3 b and the boardworking table 2 b, the mask cleaning operation for starting printing onthe subsequent board 5 can be carried forward.

The embodiments disclosed this time must be considered as illustrativein all points and not restrictive. The range of the present disclosureis shown not by the above description of the embodiments but by thescope of claims for patent, and all modifications within the meaning andrange equivalent to the scope of claims for patent are further included.

For example, while the present disclosure is applied to the printingapparatus (100, 100 a, 100 b, 100 c, 100 d, or 100 e) performing solderprinting on the printed board as the example of the board printingapparatus according to the present disclosure in each of theaforementioned first to sixth embodiments, the present disclosure is notrestricted to this. The present disclosure may alternatively be appliedto a printing apparatus of a viscous material (conductive paste such assilver paste, for example) other than solder, so far as the printingapparatus is a board printing apparatus performing board printing withscreen masks.

While the two board working tables are provided in each of theaforementioned first to sixth embodiments, the present disclosure is notrestricted to this. According to the present disclosure, one or three ormore board working tables may alternatively be provided.

While the two board working tables and the two printing tables aremovable in the direction Y in each of the aforementioned first to sixthembodiments, the present disclosure is not restricted to this. Accordingto the present disclosure, at least either the two board working tablesor the two printing tables may alternatively be movable in the directionY for the first printing and the second printing. Thus, the boardworking tables may be fixed in the direction Y, and only the printingtables may be movable in the direction Y. Alternatively, the printingtables may be fixed in the direction Y, and only the board workingtables may be movable in the direction Y. Alternatively, one of theboard working tables may be movable in the direction Y, and the other ofthe board working tables may be fixed in the direction Y, for example.

While the plate register and the plate releasing are performed by movingthe two printing tables vertically (in the direction Z) in each of theaforementioned first to sixth embodiments, the present disclosure is notrestricted to this. According to the present disclosure, at least eitherthe two board working tables or the two printing tables mayalternatively be configured to be movable vertically for the firstprinting and the second printing. Thus, the board working tables may befixed in the direction Z, and only the printing tables may be movable inthe direction Z. Alternatively, the printing tables may be fixed in thedirection Z, and only the board working tables may be movable in thedirection Z.

While the two carry-in positions En1 and En2 are provided in each of theaforementioned first to sixth embodiments, the present disclosure is notrestricted to this. One or three or more carry-in positions mayalternatively be provided.

While the two carry-out positions Ex1 and Ex2 are provided in each ofthe aforementioned first to sixth embodiments, the present disclosure isnot restricted to this. One or three or more carry-out positions mayalternatively be provided.

While the board is directly delivered from the loaders provided at thecarry-in positions En1 and En2 to the board working tables in each ofthe aforementioned first to sixth embodiments, the present disclosure isnot restricted to this. According to the present disclosure,intermediate conveyors may alternatively be provided between the loadersand the board working tables, and the board may alternatively beconveyed from the loaders to the board working tables through theintermediate conveyors, for example. Particularly in the case where onlyone carry-in position is provided, a movable intermediate conveyorcapable of distributing and conveying the board to the two board workingtables may be provided.

While the mask recognition camera and the cleaning unit are provided ineach of the board working tables in each of the aforementioned first tosixth embodiments, the present disclosure is not restricted to this.According to the present disclosure, no mask recognition camera may beprovided in each of the board working tables, or no cleaning unit may beprovided in each of the board working tables.

What is claimed is:
 1. A board printing apparatus comprising: a boardworking table holding a board to be printed on; a first printing tableand a second printing table aligned in a prescribed direction in ahorizontal direction above the board working table; and a controlportion controlling printing operations of the first printing table andthe second printing table, the first printing table holding a smallcomponent mask having a first thickness configured to perform firstprinting to print a viscous material on the board, the second printingtable holding a large component mask having a second thickness thickerthan the first thickness, formed with a relief portion having a depthlarger than the first thickness on a board contact surface to relievethe viscous material printed by the small component mask, and configuredto perform second printing to print the viscous material on the boardafter the first printing performed by the first printing table, theboard working table and at least one of the first printing table and thesecond printing table are configured to be movable in the prescribeddirection in the horizontal direction, the board working table and atleast one of the first printing table and the second printing tablebeing configured to be movable in a vertical direction, and the controlportion being configured to perform the second printing on the boardheld by the board working table by the large component mask of thesecond printing table after the first printing performed on the boardheld by the board working table by the small component mask of the firstprinting table.
 2. The board printing apparatus according to claim 1,wherein the control portion is configured to perform a printingpreparation operation of one of the first printing table and the secondprinting table during a board printing operation of the other of thefirst printing table and the second printing table.
 3. The boardprinting apparatus according to claim 2, wherein the first printingtable and the second printing table are configured to be movable in theprescribed direction in the horizontal direction, and the controlportion is configured to move the second printing table closer to aprinting position by moving the second printing table in the prescribeddirection in the horizontal direction such that a distance between thefirst printing table and the second printing table is reduced in theprescribed direction in the horizontal direction during a board printingoperation of the first printing table.
 4. The board printing apparatusaccording to claim 3, wherein the control portion is configured to movethe second printing table closer to the printing position until aninterval between the second printing table and the first printing tablebecomes an accessible minimum interval without interference during theboard printing operation.
 5. The board printing apparatus according toclaim 4, wherein the control portion is configured to locate the secondprinting table at the printing position by moving the first printingtable and the second printing table while keeping a distance equal to ormore than the minimum interval when the second printing is performed bythe second printing table after the second printing table is movedcloser to the printing position.
 6. The board printing apparatusaccording to claim 2, wherein the first printing table and the secondprinting table are configured to be movable in the vertical direction,and the control portion is configured to lower the second printing tablefrom a large component mask plate releasing height position of the largecomponent mask separated from the board after the second printing of theviscous material to a standby height position lower than the largecomponent mask plate releasing height position, where the viscousmaterial on the board is spaced from contact with the large componentmask during a board printing operation using the small component mask ofthe first printing table.
 7. The board printing apparatus according toclaim 6, wherein the standby height position is a height positiondetermined on a basis of at least the first thickness of the smallcomponent mask and an amount of deflection of the large component mask.8. The board printing apparatus according to claim 2, wherein the boardworking table includes a first board working table and a second boardworking table each configured to be movable in the prescribed directionin the horizontal direction, each of the first board working table andthe second board working table has a mask recognition camera capable ofrecognizing the small component mask and the large component mask, andthe control portion is configured to perform mask recognition of thelarge component mask of the second printing table using the second boardworking table during a board printing operation performed by the firstboard working table and the first printing table using the smallcomponent mask.
 9. The board printing apparatus according to claim 8,wherein the control portion is configured to perform the maskrecognition of the large component mask using the second board workingtable at least when a board printing operation is first performed by thefirst board working table and the first printing table.
 10. The boardprinting apparatus according to claim 2, wherein the board working tableincludes a first board working table and a second board working tableeach configured to be movable in the prescribed direction in thehorizontal direction, each of the first board working table and thesecond board working table has a cleaning unit configured to clean thesmall component mask and the large component mask, and the controlportion is configured to perform a mask cleaning operation for the smallcomponent mask of the first printing table using the first board workingtable while the second board working table and the second printing tableperform a board printing operation on the board after the first printingusing the large component mask.
 11. The board printing apparatusaccording to claim 10, wherein the first printing table and the secondprinting table are configured to be movable in the prescribed directionin the horizontal direction, and the control portion is configured tomove the first printing table in a direction away from the secondprinting table and perform the mask cleaning operation for the smallcomponent mask at a position separated from the second printing tablewhile the second board working table and the second printing tableperform the board printing operation.
 12. The board printing apparatusaccording to claim 2, wherein the board working table includes a firstboard working table and a second board working table each configured tobe movable in the prescribed direction, and the control portion isconfigured to perform at least one of operations of carrying the boardinto one of the first board working table and the second board workingtable and carrying the board out of one of the first board working tableand the second board working table during a board printing operationperformed by one of the first printing table and the second printingtable and the other of the first board working table and the secondboard working table.
 13. The board printing apparatus according to claim1, wherein the board working table includes a first board working tableand a second board working table each configured to be movable in theprescribed direction, and the control portion is configured to perform aboard printing operation of the first printing on a second board beforethe first printing by the first printing table and one of the firstboard working table and the second board working table during a boardprinting operation of the second printing performed on a first boardafter the first printing by the second printing table and the other ofthe first board working table and the second board working table.
 14. Aboard printing method of a board printing apparatus including a firstprinting table and a second printing table each configured to print aviscous material on a board, the method comprising steps of: performingfirst printing on the board held by a board working table by a smallcomponent mask of the first printing table; and performing secondprinting on the board held by the board working table after the firstprinting by a large component mask of the second printing table.
 15. Theboard printing method according to claim 14, further comprising a stepof performing a printing preparation operation performed for one of thestep of performing the first printing by the first printing table andthe step of performing the second printing by the second printing tableduring a board printing operation of the other of the step of performingthe first printing by the first printing table and the step ofperforming the second printing by the second printing table.